Scalable solar-powered desal system could supply water to homes and towns

The majority of the planet’s surface may be water, but unfortunately a heaping pile of salt makes most of that undrinkable. Desalination makes saltwater more palatable and potable, but being a bit of an energy guzzler means it isn’t the most practical solution in off-grid situations. A new system makes use of nanoparticles to harness the power of the sun and distill water more efficiently, without needing electricity.

Developed at Rice University’s Center for Nanotechnology Enabled Water Treatment (NEWT), the new system is built around the membrane distillation method, where heated salty water runs across the top of a porous membrane. Water vapor is drawn through the membrane and collects underneath in the form of purified water, but plenty of energy is lost in the process.

To improve that efficiency, the researchers harnessed the power of the sun in a system they call “nanophotonics-enabled solar membrane distillation” (NESMD). Sunlight-absorbing carbon black nanoparticles are embedded into the membrane, which helps the material harvest up to 80 percent of the sunlight that hits it, evaporating the water faster and reducing the external power that the system needs.